The compound 6,7-dihydro-5H-pyrrolo[1,2-c]imidazol-5-yl-3-fluoro-benzonitrile, its 4-(R)-enantiomer with formula (I)
and its manufacture are described in WO 2007/024945 A1, among many other compounds disclosed therein. It is known to be active as inhibitor of aldosterone synthase and aromatase.
For example, in a clinical proof-of-concept study in patients with primary aldosteronism efficiency of 4-(R)-(6,7-Dihydro-5H-pyrrolo[1,2-c]imidazol-5-yl)-3-fluoro-benzonitrile free base in inhibition of aldosterone synthase could be shown (see e.g. Amar L. et al., Hypertension 56(5), 831-838 November 2010 (Epub 2010 September).
No specific salts of the compounds mentioned in said patent application are disclosed.
Compound A in the form of free base has a quite low melting point of about 111.5° C. which constitutes a certain risk regarding physical stability of the compound during manufacture, storage and processing to pharmaceutical formulations. Thus there was a need to find specific processing conditions or specific forms of this compound that allow for stable processing.